Late Mesozoic igneous rocks in Vietnam are predominantly found in the Dalat zone (southern Vietnam), but smaller volumes also occur within southernmost Indochina (SW Vietnam-SE Cambodia). Within the latter area, six different rock suites can be distinguished based on field relations, geochemical characteristics, and zircon UPb geochronology: (1) Bay Nui-Ba Den diorite suite; (2) Bay Nui-Phnom Den granitoid suite, (3) Pha Aok granite suite, (4) Nui Sam-Angkor Borei suite, (5) Bach Ho granitoid suite, and (6) Con Dao gabbro/granite suite. These igneous rock suites indicate several pulses of magmatism during the late stages of a long-lived convergent margin. The Bay Nui-Ba Den diorite suite (ca. 107–96 Ma) is composed of monzogabbro, monzodiorite, diorite, and syenite, characterized by a metaluminous (I-type) nature, and shows several characteristics of alkali-rich primitive arc melts. The Bach Ho granitoid suite (ca. 110 Ma) consists of granodiorite and granite and displays a calc-alkaline (moderate in potassium) signature. The Bay Nui-Phnom Den granitoid suite (ca. 94–91 Ma) is the most widespread igneous group, consists mainly of granodiorite and granite of I-type affinity. These three rock suites show typical characteristics of arc-related magmatism similar to the I-type granitoids previously described in the Dalat area. The younger magmatic suites (<90 Ma) include the fined-grained granites of the Con Dao suite (ca. 83 Ma), coarse-grained two-mica granites of the Pha Aok suite (ca. 78 Ma), and fine-grained fluorite-bearing biotite granites of the Nui Sam-Angkor Borei granitoid suite (ca. 75 Ma). They display characteristics of A-type affinity with strongly negative Eu, Sr, Ba, Ti, and P anomalies. Geochemical signatures of these young igneous rocks indicate an extensional tectonic setting, possibly related to basaltic injection/asthenospheric upwelling. This additional heat input is required for partial melting of a dry residual crustal source. Geochemical and geochronological results demonstrate that the Late Mesozoic magmatism in southern Indochina can be related to two significant tectonic stages in Indochina and adjacent areas: (1) the Paleo-Pacific subduction (110–90 Ma) and (2) a transitional phase leading to the opening of the South China Sea (83–75 Ma).

越南晚中生代火成岩主要分布在大叻地区（越南南部），但最南端的印度支那（西南越南至柬埔寨）也有较小的体积。在后一个区域内，可以根据场关系，地球化学特征和锆石U区分出六个不同的岩石组。铅地球年代学：（1）Bay Nui-Ba Den闪长岩组；（2）Bay Nui-Phnom Den花岗岩套房，（3）Pha Aok花岗岩套房，（4）Nui Sam-Angkor Borei套房，（5）Bach Ho花岗岩套房和（6）Con Dao gabbro /花岗岩套房。这些火成岩套件表明，在一个长久的会聚边缘的晚期，有几处岩浆作用脉动。Bay Nui-Ba Den闪长岩组（约107–96 Ma）由辉石，辉闪岩，闪长岩和正长岩组成，具有金属（I型）性质，并显示出富含碱的原始电弧熔体的几个特征。巴赫霍花岗岩类套房（约110 Ma）由花岗闪长岩和花岗岩组成，并显示出钙碱性（钾含量中等）的特征。Bay Nui-Phnom Den花岗岩组（大约94-91 Ma）是最广泛的火成岩群，主要由花岗闪长岩和I型亲和力花岗岩组成。这三个岩石套件显示出与弧有关的岩浆作用的典型特征，类似于先前在大叻地区描述的I型花岗岩。较年轻的岩浆套件（<90 Ma）包括Con Dao套件的细粒花岗岩（约83 Ma），Pha Aok套件的粗粒两云母花岗岩（约78 Ma）和细粒Nui Sam-Angkor Borei花岗岩套件中的含萤石黑云母花岗岩（约75 Ma）。它们显示出具有强烈负Eu，Sr，Ba，Ti和P异常的A型亲和力特征。这些年轻火成岩的地球化学特征表明其伸展构造背景，可能与玄武岩注入/软流圈上升有关。对于干燥的残留地壳源的部分熔化，需要此额外的热量输入。